The primary objective of this effort is to develop a program which will have the ultimate capability of testing the mutagenicity of 1,000 chemicals per year using microbial systems, and an as-yet-undetermined smaller number of chemicals in higher in vitro and in vivo test systems. The major component of this development process will be test system validation, which includes; (1) reproducibility, (2) comparison with other mutagenicity tests, (3) comparison of the carcinogenesis tests, and (4) structure/activity relationships. Since the volume of data generated in this program will be large, an important ancillary aspect will be the development of computer holding and processing procedures.